Switch structure



.Sept 'M9 1934., M, E HENNING 31,973,253

SWITCH STRUCTURE Filed Feb. 23, 1952 fm1 if 3f Patented Sept. 11, 1934 UNITED STATES SWITCH STRUCTURE Malcolm E. Henning, Des Moines, Iowa, assignor to Penn Electric Switch Co., Des Moines, Iowa,

a corporation of Iowa Application February 23, 1932, Serial No. 594,578 6 claims. (C1. 20o- 138) An object of my present invention is to provide aswitch structure for use in connection with a fuel burner and a room thermostat, said switch structure being responsive to combustion in the fuel burner and operating to eliminate, as far as possible, combustion failure in a furnace and to deenergize the fuel burner'in the event of combustion failure.

A further object is to provide a control switch structure having combustion responsive mechanism and a pair of switches operable thereby, said switches being normally in closed position for energizing the fuel burner, one of them being operated by the combustion responsive mechanism to open position upon high temperature conditions in the furnace as caused during normal operation thereof and the other to open position upon low temperature conditions as caused by combustion failure.

Still a further object is to connect the switches with a room thermostat to operate in conjunction therewith for controlling the fuel burner, one of the switches being series connected with the room thermostat and the other being shunt connected therewith and also series connected with the other switch.

Still a further object is to provide a control switch structure in which one switch acts as a safety switch because of combustion failure, means being provided to manually reset such switch when the cause for combustion failure has been remedied. l

Still another object is to provide a switch structure for the purpose of maintaining fire in a combustion chamber independent of a room thermostat and, in case of the fire going out for some unforeseen cause, theswitch is opened to prevent excess coal being forced into the combustion chamber of the furnace.

A further object is to provide a switch structure which prevents excessive operationV of a stoker in the event of fuel failure, the switch providing a complete shut-down so that it is necessary to provide additional fuel, ignite it and reset the switch structure manually before automatic operation can be resumed.

With these and other objects in view my invention consists in the construction, arrangement and combination of the various parts of my device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawing, in which:

Figure 1 is a front elevation of a control switch 55 embodying my invention.

Figure 2 is an enlarged, longitudinal sectional View through the upper left hand portion of Figure l.

Figure 3 is a sectional view on the line 3 3 of Figure 1.

Figure 4 is a perspective view of reset mechanism; and

Figure 5 is a diagrammatic view .showing my control switch connected with a room thermostat and a fuel burner or stoker for a furnace.

On the accompanying drawing I have used the reference numeral 10 to indicate a switch housing. The housing 10 is preferably formed of insulation. It is provided with a cover 12 to enclose the switch mechanism within the housing. 70

A hub 14 extends from the switch housing 10 and is adapted for mounting in the wall of a chimney or a stack or in the Wall of a furnace. A rod 16 extends through the hub 14 and is rotated by a bi-metallic coil 18, which is responsive to combustion temperature. The coil 18 has one end secured at 20 to the rodv16 and its other end anchored at 22 to the hub 14. The rod 16 extends through a bushing 24 (see Figure 2) Which also serves as a means of connection between the switch housing 10 and the hub 14.

Adjustably mounted on the left end of the rod 16 is an actuating finger 26 adapted to engage stops 28 which are secured to a sleeve 30. The stops 28 are adjustable relative to the sleeve so as to adjust the device to different desired temperatures and the spacing between the stops 28 provides for normal movement of the nger 26 without moving the sleeve 30 as will hereinafter become obvious.

To prevent undesired rotation of the sleeve 30 while the finger 26 is between the stops 28, springs 29 are arranged in sockets of the housing 10 and frictionally engage a disk 31. The stops 28 are xed relative to the disk 31.

Slidably mounted on the sleeve 30 is a cam A, having cam surfaces 32 and 34. A slot 36 in the sleeve 30 receives a reduced end of a set screw 38 to provide for sliding but non-rotating movement of the cam A relative to the sleeve 30. The cam is held in one limit of its movement relative to the sleeve by a spring 40.

A manually operable reset member B is provided for the cam A in the form of a plate mounted on the housing 10 by screws 42. Slots 44 are pro- 10b vided in the plate for the screws, which are of shouldered type, to extend through whereby the member B is slidably mounted relative to the housing 10. The member B has a finger 46 adapted to engage the cam A. The member B is held at one limit of its sliding movement by a spring 48 having one end anchored to a rivet 50 and its other end engaged in an opening in the nger 46.

Within the housing 10 a main switch arm 52 is pivoted at 54. A resilient bell crank lever 56 is also pivoted at 54 and has one end engaging the cam surface 32 and its other end engaging the switch arm 52. A stationary contact 64, mounted on a contact plate 64a, is adapted to be engaged by a contact 66 on ythe arm 52. The arm 52 is an armature inuenced by the poles 65 of a peranent magnet. The magnet 65 insures snap ction of the switch arm 52 to open position when the cam surface 32 tends to move it to such open position, the spring 56 during such operation being tensioned until the built up energy therein can overcome the magnetic pull of the poles 65 on the armature arm 52.

An auxiliary switch arm 58 is pivoted at 60. A resilient bell crankflever 62 engages the cam surface 34 and the switch arm 58 which is an armature inuenced by a magnet 69. .A` stationary contact 68 is mounted on a contact plate 68a and the auxiliary switch arm 58 carries a contact 70 engageable with the contact 68.

At the back of the-switch housing 10 terminals '12, 74 and '76 are located. The terminal 72 connects with the contact 62, the terminal '74 with the contacts 66 and '10 and the terminal '76connects with the contact 68. All this is diagrammatically shown in Figure 5.

The particular switch structure herein disclosed `is adapted for use in connection with a furnace C, a stoker 80, a stoker motor 82 and a room thermostat 84. The bimetallic coil 18 extends into the stack '78 of the furnace C, or into any part of the furnace in which the temperature is raised by combustion establishment.

Tracing out the wiring in Figure 5, it will be obvious that the main switch contacts 64 and 66 are connected in shunt with the room thermostat 84 and the auxiliary contacts 68 and 70 are series connected with both the room thermostat and the main switch. Y

In Figure 3 hot, normal and too cold 'positions are indicated for the cam A. Also, the positions of the main and auxiliary switches 52 and 58 corresponding to the hot, "normaP and too cold positions of the cam A are indicated. The cam surfaces 32 and 34 are of similar height but the levers 56 and 62 are arranged so that when the cam surfaces 32 and 34 engage the levers 56 and 62 the main switch arm 52 is in closed position and the auxiliary switch arm 58 is in open position as shown in Figure 1. This is the too cold position.

There is a notch 33 shown'in Figure 3 at the normal position which allows the auxiliary switch lever 58 to close when the notch is in registry with the lever 62. Further movement of the cam A to hot position does not affect the switch lever 58 because of a cam surface 35 which is the same depth as the notch 33 and is a` con- -tinuation of the cam surface 34. Beyond the Practical operation In the operation of the switch structure herein disclosed, assuming that the fuel has been ignited and combustion thereby established in the furnace C, the notch 33 of the cam A will register with the leaf springs 66 and 62 for permitting the main and auxiliary switch arms 52and 58 to assume their closed circuit positions because of the magnets 65 and 69. The room thermostat 84 will of course, be in closed circuit position because of the room being cold'and the stoker will operate until both the main switch lever 52 and the room thermostat are in open circuit positions. Thereafter, during the normal automatic operation of the structure, when the room temperature recedes to a predetermined` degree the contacts in the room thermostat 84 will become engaged for starting the operation of the furnace until the room thermostat is again satised. In mild weather especially, the re may get very low or go out entirely because of the long intervals of time between theclosing operations of the room thermostat 84. My switch structure is accordingly provided with the main switch 52 which closes upon a low temperature condition in the furnace C as caused by a low fire therein. This causes another operation of the stoker until the temperature in the furnace has risen sufficiently to cause the cam A to assume the hot position. The hotposition refers to the condition of the furnace and notlthe room in which the room thermostat 84 is mounted and if after the switch 52 is opened the room is not warm enough the room thermostat 84 will cause continuation of the operation of the stoker until the circuit is broken in the room thermostat. y

Upon complete combustion failure, the furnace C will cool oi to a lower than normal position or a "too cold position, whereupon the auxiliary switch 58 will open for shutting down the operation of the structure regardless of whether the main switch 52 or the room thermostat 84 are in the closedvcircuit position or not. This occurs moving the reset member B to the vdotted line position of Figure 1. This removes the cam surface 34 from the path of the lever 62 so that the magnet 69 will close the auxiliary switch 58. The

reset member B may then be released.

Upon release of the member B the spring in Figure 1 and the spring 40 tends to move the cam A to its initial full line position. The upper 4s moves it to its initial position shown by solid lines end of the lever 62, however, is in the way and holds the cam A in the dotted line position so that the structure can continue to operate even though the cam A is in a too cold position. After the furnace heats up, however, the bimetallic coil 18' will move the cam A to the normal position whereupon the notch 33 will be inregistry wi'th the lever 62 and the spring 40 will then return the cam A to its initial position for automatic operation. Thereafter the switch structure will operate automatically through normal andfhot positions until combustion failure again moves the cam A to too cold position.-

Some changes may be made in the construction and arrangement of the parts of my devic'e without departing from the real spirit 'and purpose of my invention, and it is my intention to Y cover by my claims any modifiedforms'of structure or use of mechanical equivalents, which may be reasonably included within their scope.

I claim as my invention:

l. In a device of the class described, an actuating mechanism, a pair of control mechanisms engaged therewith and movable from normal position thereby, one of said control mechanisms being movable by movement of the actuating mechanism in one direction and the other one being movable by movement of the :actuating mechanism in an opposite direction, one of said control mechanisms being entirely automatically operated by said actuating mechanism manual reset means, the other of said control mechanisms being both automatically operated by said actuating mechanism and also operable manually by said manual reset means for reset purposes.

2. A high and low temperature actuated control device comprising temperature responsive mechanism and a pair of switches, means constraining said switches to remain normally in closed position, said temperature responsive mechanism being operatively associated with one of them to open it by movement of the temperature responsive mechanism to high temperature position and said temperature responsive mechanism being operatively associated with the other one to open it by movement of the temperature responsive mechanism to low temperature position, and manually resettable means for one of said switches to close it while the temperature responsive mechanism is in position tending to open it.

3. A high and low temperature actuated control device comprising temperature responsive' mechanism and a pair of switches, means constraining said switches to remain normally in closed position, said temperature responsive mechanism being operatively associated with one of them to open it by movement of the temperature responsive mechanism to high temperature position and said temperature responsive mechanism being operatively associated with the other one to open it by movement of the temperature responsive mechanism to low temperature position and means to close one of said switches after it has been opened by said temperature responsive mechanism and to maintain it in closed position until the temperature responsive mechanism moves to normal position.

4. A control structure for an electric circuit comprising a pair of switches in series in the electric circuit, common actuating mechanism operatively cooperable with each of said switches for moving one of them to circuit making and circuit breaking positions upon normal operation of said actuating mechanism and moving the other of them to circuit breaking position upon non-normal operation of said actuating mechanism and manual means for resetting said last mentioned switch by moving it to circuit making position while said actuating mechanism remains in the position it assumes upon non-normal operation and for retaining it in such circuit making position until the cause for the non-normal'operation of said actuating mechanism has been removed.

5. A control structure for an electric circuit comprising a, pair of switches in series in the electric circuit, common actuating mechanism operatively cooperable with each of said switches for moving one of them to circuit making and circuit breaking positions upon normal operation of said actuating mechanism and moving the other of them to circuit breaking position upon non-normal operation of said actuating mechanism and manual means for resetting said last mentioned switch by` moving it to circuit making position while said actuating mechanism remains in the position it assumes upon non-normal operation and for retaining it in such circuit making position until the cause for the non-normal operation of said actuating mechanism has been removed, and spring means for returning said manual means after the resetting of said second switch to circuit making position has become complete.

6. In a device of the class described, an actuating mechanism movable to a central and two opposite positions, a pair of control mechanisms movable from operative positions thereby, one of said control mechanisms being so movable by movement of the actuating mechanism to one of its opposite positions and the other one being so movable by movement of the actuating mechanism to its other opposite position and manually releasable means to retain it in said other opposite position and both control mechanisms being in operative positions when said actuating mechanism is in said central position.

MALCOLlVI E. 

